U.S. patent application number 13/963543 was filed with the patent office on 2014-10-23 for method and apparatus for enhancing heat transfer in a fluid container.
The applicant listed for this patent is Grant BLANDIN, Claude BOURGAULT, Cliff WIEBE. Invention is credited to Grant BLANDIN, Claude BOURGAULT, Cliff WIEBE.
Application Number | 20140311707 13/963543 |
Document ID | / |
Family ID | 51728126 |
Filed Date | 2014-10-23 |
United States Patent
Application |
20140311707 |
Kind Code |
A1 |
WIEBE; Cliff ; et
al. |
October 23, 2014 |
METHOD AND APPARATUS FOR ENHANCING HEAT TRANSFER IN A FLUID
CONTAINER
Abstract
An apparatus and method for enhancing the transfer of heat in a
fluid within a reservoir. The interposition of heat exchangers
between a primary heating arrangement and an auxiliary heating
arrangement results in greater utilization efficiency in heat
transfer to the fluid within the container. A predetermined
arrangement of heat exchangers within the reservoir containing the
same is also disclosed.
Inventors: |
WIEBE; Cliff; (Calgary,
CA) ; BOURGAULT; Claude; (St. Brieux, CA) ;
BLANDIN; Grant; (St. Brieux, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WIEBE; Cliff
BOURGAULT; Claude
BLANDIN; Grant |
Calgary
St. Brieux
St. Brieux |
|
CA
CA
CA |
|
|
Family ID: |
51728126 |
Appl. No.: |
13/963543 |
Filed: |
August 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61813317 |
Apr 18, 2013 |
|
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|
Current U.S.
Class: |
165/64 |
Current CPC
Class: |
E21B 36/00 20130101;
E21B 43/26 20130101; F28F 3/14 20130101; Y02E 60/14 20130101; F24H
9/2021 20130101; F28D 2020/0078 20130101; F24H 1/186 20130101; Y02E
60/142 20130101; F28D 20/0034 20130101 |
Class at
Publication: |
165/64 |
International
Class: |
F24H 9/18 20060101
F24H009/18 |
Claims
1. A method of enhancing utilization efficiency of heat exchange in
a fluid retained in a reservoir, comprising: providing a heater
circuit having a primary heater for heating a reservoir heat
exchanger disposed within said reservoir; providing an auxiliary
heater; and interposing a secondary heat exchanger in fluid
communication between said primary heater, said auxiliary heater
and said reservoir heat exchanger to augment heat content of cool
fluid returning from said reservoir heat exchanger with heat from
said primary heater and said auxiliary heater.
2. The method as set forth in claim 1, further including the step
of disengaging said auxiliary water heater and said secondary heat
exchanger upon reaching a predetermined fluid temperature in said
reservoir.
3. The method as set forth in claim 2, further including engaging a
disengaged auxiliary water heater and said secondary heat exchanger
on a heater circuit having said primary heater and reservoir with
said reservoir heat exchanger for enhancing said utilization
efficiency of heat exchanger at least until said predetermined
temperature is reached.
4. The method as set forth in claim 1, wherein at least two heater
circuits are connected to said auxiliary heater and said secondary
heat exchanger.
5. The method as set forth in claim 1, wherein said reservoir
comprises a fracturing fluid reservoir for retaining fracturing
fluid.
6. The method as set forth in claim 1, further comprising a water
reservoir for retaining water.
7. The method as set forth in claim 1, further comprising a
drilling fluid reservoir for retaining drilling fluid.
8. The method as set forth in claim 1, further comprising an acid
reservoir for retaining acid.
9. The method as set forth in claim 1, including providing a
plurality of reservoir heat exchangers in spaced relation disposed
within said reservoir.
10. The method as set forth in claim 9, further including the step
of positioning said reservoir heat exchangers in said reservoir to
be spaced from the bottom of said reservoir.
11. The method as set forth in claim 9, wherein said reservoir heat
exchangers are positioned in an angular relationship relative to
the bottom of said reservoir.
12. The method as set forth in claim 11, wherein said angular
relationship is between 0.1 degrees and 90 degrees relative to the
horizontal bottom of said reservoir.
13. The method as set forth in claim 12, wherein said angular
relationship is between 15 degrees and 20 degrees.
14. The method as set forth in claim 9, wherein said reservoir heat
exchangers are spaced in a predetermined relationship relative to
one another to facilitate natural convection.
15. The method as set forth in claim 14, wherein the relative
distance between adjacent heat exchangers increases in a counter
clockwise direction.
16. The method as set forth in claim 12, wherein the relative
distance is between the ratio of 1:1 to 1:1.7.
17. The method as set forth in claim 16, wherein the relative
distance is 1:1.5.
18. The method as set forth in claim 1, further including engaging
a disengaged auxiliary water heater and secondary heat exchangers
on a heater circuit having said primary heater and reservoir with
said reservoir heat exchangers for enhancing said utilization
efficiency of heat exchange at least until said predetermined
temperature is reached.
19. The method as set forth in claim 1, characterized in that at
least two heater circuits are connected to said auxiliary heater
and said second heat exchanger.
20. The method as set forth in claim 1, characterized in that said
reservoir comprises a fracturing fluid reservoir for retaining
fracturing fluid.
21. A system for enhancing the rate of heart exchange in a fluid
retained in a reservoir, comprising: a heater circuit having a
primary heater for heating a reservoir heat exchanger disposed
within said reservoir; an auxiliary heater; and a secondary heat
exchanger interposed and in fluid communication between said
primary heater, said auxiliary heater and said reservoir heat
exchanger to augment heat content of cool fluid returning from said
reservoir heat exchanger with heat from said primary heater and
said auxiliary heater.
22. The system as set forth in claim 21, further including a
reservoir.
23. The system as set forth in claim 18, characterized in that said
reservoir is a fracturing fluid reservoir.
24. The system as set forth in claim 21, characterized in that said
reservoir heat exchanger comprises a planar configuration.
25. The system as set forth in claim 24, wherein said heat
exchanger is self-contained and includes a plurality of impressions
over the surface area thereof.
26. The system as set forth in claim 25, wherein said impressions
comprise dimples.
27. The system as set forth in claim 25, wherein said system
includes a plurality of reservoir heat exchangers.
28. The system as set forth in claim 27, wherein said reservoir
heat exchanger of said plurality of reservoir heat exchangers
includes a heater circuit and a secondary heat exchanger.
29. The system as set forth in claim 25, further including a
temperature monitor at least provided in said reservoir.
30. The system as set forth in claim 21, characterized in that said
system is a portable system.
31. The system as set forth in claim 21, characterized in that said
system is self-contained and independent of a vehicle in use.
32. The system as set forth in claim 21, characterized in that said
auxiliary heater and said secondary heater exchanger are connected
to a plurality of heater circuits.
33. An apparatus for enhancing utilization efficiency of the rate
of heat exchange in a fluid retained in a reservoir having a heater
circuit having a primary heater for heating a reservoir heat
exchanger disposed within said reservoir, the improvement
comprising: an auxiliary heater; and a secondary heat exchanger
interposed and in fluid communication between said primary heater,
said auxiliary heater and said reservoir heat exchanger to augment
heat content of cool fluid returning from said reservoir heat
exchanger with heat from said primary heater and said auxiliary
heater.
34. The apparatus as set forth in claim 32, wherein said auxiliary
heater and said secondary heat exchanger are portable.
35. The apparatus as set forth in claim 33, wherein said auxiliary
heater and said secondary heat exchanger are connected to a
plurality of heater circuits.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method of enhancing the
efficiency of heat transfer into a liquid fluid container and more
particularly, the present invention relates to a method, system and
apparatus for efficiently transferring heat into a fluid requiring
the maintenance of a certain temperature in order to have the fluid
remain effective.
BACKGROUND OF THE INVENTION
[0002] Fluid heating arrangements have been known for many years
and these permeate a wide variety of industries. One industry where
the temperature maintenance of the fluid is important is in the
fracturing fluid heating industry. As is known "frac" fluid
requires heating in order to be effective in an oil field
operation. The temperature of the frac fluid must be maintained at
certain temperatures in order to prevent fallout of sand within the
fracturing environment.
[0003] A panoply of methods and different apparatuses to effect the
method have been proposed in the prior art. An example of one such
arrangement is one that which is shown and used by McAda Fluids
Heating Services. The arrangement provides a truck arrangement
where hot oil is used. The arrangement requires the use of fairly
significant equipment that is transported to the site by a tractor
trailer vehicle. In some instances, the vehicle must remain at the
job site in order to provide for the necessary equipment to be
available for heating the frac water.
[0004] A further variation of the frac water heating systems is
shown in the website of Rapid Hot Flow LLC. In the website, there
is an indication that Rapid Hot Flow's heating trucks are equipped
with 21 million BTU input updraft style burner that runs on
propane. It is indicated that once the heater trucks arrive at the
specified location, the trucks can be heating within minutes. There
is a further indication that when the hoses are connected, and the
trucks have started circulating water, an operator runs through a
list of procedures to ensure that all the requirements have been
met. In this system, it is obvious that the vehicle is an integral
part of the heating system and further that there is input required
by the operator.
[0005] A further variation on the concept of maintaining the
temperature of the frac water in the reservoir is shown on the
Powerblanket website where effectively a blanket or a tank wrap is
positioned around the holding tank. In the website there is an
indication that the tank wrap creates a barrier of insulation to
keep fluids from freezing and viscous materials flowing.
[0006] Although this is generally useful, it appears to be quite
cumbersome not only from a handling point of view, but also for
positioning about the tank. It is well known that holding tanks or
reservoirs are very large and it would be somewhat cumbersome to
wrap the blanket about a large vessel.
[0007] Turning to the patent art, in U.S. Pat. No. 5,983,889,
issued Nov. 16, 1999, to Thomas, there is disclosed a portable
water tank heating system. The reference teaches a portable system
which uses a hollow continuous tubular loop containing a fluid this
is circulated through the loop by convection to prevent water in
the tank from freezing. The fluid in the loop flows from a
reservoir and travels past a gas burner in the hot chamber for
heating the fluid. The fluid flows through a heat exchanger and
releases heat to the cold water in the tank before being returned
into the housing through the return line. The fluid then returns to
repeat the cycle.
[0008] The system would appear to completely rely on the burner
coil for transmitting the heat to the water body. It is well
established that such arrangements have limited efficiency.
[0009] In United States Patent Publication No. US 201110211818,
published Sep. 1, 2011, the Applicant, Grady, teaches a fracturing
tank fluid heating tank.
[0010] This patent application is very broad and effectively
provides a self contained tank into which is disposed in a
fracturing tank fluid healing unit. In the document, the tank
comprises a closed tank having an access point such as a manhole
cover. The unit further includes a dimensional coil where a tube
like heating unit is designed to heat the fluid once contained
within the tank.
[0011] As with the previous reference, this reference is confined
to a relatively inefficient heating means in terms of the coil type
arrangement. The inefficiency in terms of the energy is pronounced;
in arrangements with the heat exchanger in the tank only,
efficiency is typically 50%.
[0012] Chandler, in United States Patent Publication No.
US2010/0000508, published Jan. 7, 2010, teaches an oil fired frac
water heater. The document teaches a portable system for heating
treatment fluids at a remove worksite. The arrangement has a
firebox, heat exchanger within the firebox, a fluid supply system
including a fluid supply pump connected to an inlet of a tubular
coil associated with the heat exchanger and a plurality of burner
assemblies in the firebox. The arrangement further provides for a
primary air system for supplying pressurized air flow to each of
the burners and a secondary air system for supplying a second
pressurized air flow to the firebox. The secondary pressurized air
flow increases the convective heat transfer of thermal energy from
the combustion flow to the treatment fluid. The arrangement is
fairly complex and does not indicate any thermal energy augmenting
system which would elevate the efficiency of the unit.
[0013] In U.S. Pat. No. 6,516,754, issued Feb. 11, 2003, Chadwick,
teaches a convective heating system for liquid storage tanks. The
arrangement incorporates a heating chamber with an inlet and an
outlet for convective fluid flow past a flameless heater. Heated
liquid is circulated through the upper outlet of the tank from the
heating chamber and back into the tank. It is indicated that the
heated liquid reenters the tank through a floating discharge
flexibly connected to the upper section of the tank to remain
dynamically in contact with the liquid at all times. This is said
to avoid airlocks which interrupt the convective flow of liquid
through the heating system.
[0014] Hefley, in United States Patent Publication No.
US2010/0294494, published Nov. 5, 2010, teaches a water heating
apparatus for continuous heated water flow and method for use in
hydraulic fracturing. Essentially, the publication includes a
discussion regarding mixing device for ensuring that the frac fluid
is maintained at the proper temperature during operation.
[0015] Other references which are generally relevant to the area of
technology of the instant application include U.S. Pat. Nos.
2,067,063; 3,933,205; 3,512,239; 3,937,275; 4,318,549; 5,115,491;
6,662,861; 7,793,707; and United States Patent Publication Nos. US
2006/0196958; US 2007/0000453; US 2008/0217420; US 2008/0236275; US
2008/0206699; US 2010/010156; and US 2010/0193155.
[0016] Despite the comprehensive prior art and numerous methods
that have been set forth in the fracturing frac fluid heating
methods, there still exists the need to improve on the existing
systems and operation where heat transfer can be maximized using a
portable system and further where there is not any requirement that
the vehicle be present at all times for operation.
[0017] The present invention has successfully unified various
technologies in a unique manner to result in an elegant solution
for maximizing heat energy in a frac fluid environment. It will be
appreciated by those skilled that the fluid referred as frac fluid
could be any fluid, drilling water, acid, inter alia.
SUMMARY OF THE INVENTION
[0018] One object of the present invention is to provide an
improved method, system and apparatus for augmenting the heat
enthalpy available for transfer into a frac fluid or other fluid in
an efficient manner.
[0019] A further object embodiment of embodiment of the present
invention is to provide a method of enhancing the rate of heat
exchange in a fluid retained in a reservoir, comprising: providing
a heater circuit having a primary heater for heating a reservoir
heat exchanger disposed within the reservoir; providing an
auxiliary heater; and interposing a secondary heat exchanger in
fluid communication between the primary heater. The auxiliary
heater and the reservoir heat exchanger is present to augment heat
content of cool fluid returning from the reservoir heat exchanger
with heat from the primary heater and the auxiliary heater.
[0020] Conveniently, the use of the secondary heat exchanger within
the environment of the other components which are high efficiency,
results in significant operational efficiency for heating the frac
fluid. Any of the suitable heat exchangers may be used such as
those manufactured by the Dry Air Corporation, the Alfa Laval
Corporation. The Alfa Laval unit is referred to as a brazed plate
heat exchanger (CB Series). Of particular convenience is the fact
that the heat exchanger arrangement can be incorporated without
significant increase in mass or footprint to the overall heating
arrangement. In one of embodiment, the entire heating arrangement
can be configured and loaded onto a single skid and easily
transported to a worksite and left at the worksite to therefore
free the use of the transporting vehicle for other purposes.
Further, the unit can be remotely controlled to avoid significant
operator input and repetitive visits to the worksite with
replacement heating units which would result in heavy traffic flow
at the worksite. As noted supra, the utilization efficiency of
existing arrangements is typically 50%; by incorporating the
instant technology, utilization efficiency can reach 100%. This
represents a significant advance in the art.
[0021] It has been found that by incorporating an auxiliary heater
together with the secondary heating exchanger, the overall
utilization efficiency of the system can be significantly
increased. The result is that the secondary auxiliary heater
functions to warm, cool fluid within the heat exchanger system
leaving the frac fluid reservoir. In this manner, there is
effectively a dual heating process taking place, namely one from
the auxiliary heater and the second from the heater circuit from
the primary heater. By the introduction of the heat exchanger, the
method may be optimized in terms of output utilization
efficiency.
[0022] In accordance with a further object of one embodiment of the
present invention, there is provided a system for enhancing the
rate of heat exchange in a fluid retained in a reservoir
comprising: a heater circuit having a primary heater for heating a
reservoir heat exchanger disposed within the reservoir; an
auxiliary heater and a secondary heat exchanger interposed and in
fluid communication between the primary heater, the auxiliary
heater and the reservoir heat exchanger to augment heat content of
cool fluid returning from the reservoir heat exchanger with heat
from the primary heater and the auxiliary heater.
[0023] The system incorporates a highly efficient reservoir heat
exchanger. It has been found that by making use of a dimpled closed
heat exchanger of planar configuration, in combination with the
secondary heat exchanger and heater circuit, as well as auxiliary
heater, results in a very effective compact modular system. The
dimpling effect of the heat exchanger within the reservoir
significantly increases the available surface area for heat
transfer. The exchanger, as noted above, is closed and uses for
example, propylene glycol as the heating fluid for transferring the
heat enthalpy sensed by the fluid.
[0024] In accordance with a further object of one embodiment of the
present invention, there is provided an apparatus for enhancing the
rate of heat exchange in a fluid retained in a reservoir having a
heater circuit having a primary heater for heating a reservoir heat
exchanger disposed within the reservoir. The improvement comprises
an auxiliary heater; and a secondary heat exchanger interposed and
a fluid communication between the primary heater, the auxiliary
heater and the reservoir heat exchanger to augment heat content of
cool fluid returning from the reservoir heat exchanger with heat
from the primary heater and the auxiliary heater.
[0025] Having thus generally described the invention, reference
will now be made to the accompanying documents illustrating
preferred embodiments.
[0026] Copious advantages flow from the practice of the methodology
and use of the apparatus. These include: [0027] i) the lack of
moving parts; [0028] ii) the portability of the arrangement due to
the reduced size; [0029] iii) lighter weight for certain
embodiments; [0030] iv) reduced capital cost; [0031] v) no fluid
mixing of fluid to be heated with the heat exchanger fluid; [0032]
vi) expedited assembly of the apparatus; [0033] vii) the ability to
use the main generator; and [0034] viii) no extraction of the
fluids in the tanks, therefore avoiding fluid leaks from the
tank.
INDUSTRIAL APPLICABILITY
[0035] The invention has utility in the head transfer art,
[0036] Having thus generally described the invention, reference
will now be made to the accompanying drawings, illustrating
preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a schematic illustration of the apparatus employed
to effect the method according to one embodiment;
[0038] FIG. 2 is a schematic illustration of the heat exchange
system according to one embodiment;
[0039] FIG. 2A is a further variation of FIG. 2;
[0040] FIG. 3A is a schematic illustration of the reservoir heat
exchanger according to one embodiment;
[0041] FIG. 3B is a side view of FIG. 3A;
[0042] FIG. 4 is a plan view of the heat exchanger in FIG. 3A;
[0043] FIG. 5 is a section along line 5-5 of FIG. 4;
[0044] FIG. 6 is a top view of the reservoir illustrating the
positioning of the heat exchangers; and
[0045] FIG. 7 is a top view of an alternate embodiment.
[0046] Similar numerals used in the Figures denote similar
elements,
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] Referring now to FIG. 1, schematically depicted is the
overall apparatus employed as an example. The overall arrangement
is denoted by numeral 10. A reservoir 12 retains a fluid, one
example of which is fracturing fluid, commonly referred to as
"frac" fluid. Such vessels typically include a liner 14 which
secured to the reservoir by, for example, clamps or other suitable
fasteners 16 (not shown). As is well known to those skilled in the
art, frac fluid needs to be maintained at an elevated temperature
in order to be useful. This requires the injection of heat into the
fluid.
[0048] Heat injection in the example is achieved by making use of a
modular heating station, generally denoted by numeral 18. With the
instant technology, the station 18, is particularly effective since
it is retained on a skid 20 which may be easily transported to a
worksite and disengaged from a truck for use. This has the
advantage of preventing the invasiveness of several trucks at the
site for prolonged periods and avoiding the concomitant costs and
environmental impact. The skid and ancillary equipment is thus
independent of a vehicle in use and therefore is self-contained.
The skid 20 includes a plurality of heaters 22, generator 24,
storage tank 26 for a heat transfer liquid, such as propylene
glycol, fuel tank 30, inter alia. The heaters 22 each include
secondary heat exchangers 32 which will be discussed in greater
detail herein after. A plurality of fluid lines 34 fluidly
communicate with reservoir 12 and more particularly with reservoir
heat exchangers 36 which will now be discussed with respect to FIG.
2.
[0049] FIG. 2 is a schematic representation of the overall layout
in accordance with one example. Reservoir heat exchangers 36, shown
as two such units in the example for purposes of explanation, are
planar elements and will described in detail later in the
specification. The units 36 fluidly communicate with the water
heaters 22 by lines 34 supra and 38. Conventionally, the water
heaters 22 would simply run heating fluid, such as glycol, through
heating units positioned in the tank 12 to heat the fluid retained
in the reservoir. In the present system, by making use of ancillary
heaters and interposition of secondary heat exchangers, utilization
efficiency has been greatly improved with a complementary small
portable system.
[0050] The secondary heat exchangers 32 are interposed in fluid
communication with the heaters 22 and reservoir heat exchangers 36
as well as auxiliary heater 40. In operation, cool water from the
reservoir heat exchangers 36 denoted by A on line 34 enters a
respective secondary heat exchanger 32.
[0051] From the respective exchanger 32 cool fluid exits each
exchanger 32 as stream B and with passive enthalpy transfer at C.
Stream C then enters auxiliary water heater 40 where it is heated
exiting as stream D for introduction back into the individual
exchangers 32 as separate streams E. Streams E exit the respective
exchangers 32 as warmed streams F for introduction into the heaters
22 for upgrade heating to hotter streams exiting the respective
heaters 22 as stream G. The latter are then introduced into the
reservoir heat exchangers 36. In this manner of operation, the
utilization efficiency of the system is significantly boosted while
avoiding the use of vehicle based power, heavy equipment and costly
human intervention.
[0052] Referring now to FIG. 2A, shown is a further embodiment of
the method. In this embodiment, hot fluid exists primary heater 22
via stream G and travels through heat exchanger 36 exiting cold via
stream A. Cold fluid enters heat exchanger 32 receiving heat via
passive transfer from auxiliary heater 40 and particularly by
stream D and exits heat exchanger 32 wam 1 via stream F returning
to primary heater 22. This is generally the primary circuit.
Subsequently, hot fluid exists auxiliary heater 40 via stream D and
travels through heat exchanger 32 (or heat exchangers in
applications where one auxiliary unit is used to boost more than
one primary circuit) transferring heat passively to primary stream
F, returning cool to auxiliary heater 40 via stream C. This is
referred generally as the second circuit.
[0053] Of particular advantage is the fact that the method and
apparatus related to FIG. 2A allows the second circuit component
(auxiliary heater 40 and heat exchanger 32 and related connections)
to be removed from the primary circuit, once the desired
temperature has been reached in the tank. The secondary circuit
could then be transported to another tank to elevate the
utilization efficiency and heat the contents of the tank. In this
manner, for the arrangements of FIG. 2A the secondary circuit
functions as an optimization module.
[0054] Returning now to the reservoir heat exchangers 36, FIGS. 3A,
38, 4 and 5 illustrate the structure in more detail. The
arrangement as noted above is planar and generally rectangular in
the example. The exchanger 26 includes an inlet connection 40 and
an outlet connection 42 in a sealed body. For enhanced efficiency,
the entire surface area of the exchanger 26 is dimpled, the dimples
being denoted by numeral 44. This is more clearly illustrated in
FIGS. 4 and 5 where the exchanger is shown in plan view. As shown,
the dimples 44 extend over the Whole area of exchanger 26. A cross
section of the exchanger 26 is shown in FIG. 5. The heating fluid,
using glycol as the example, flows through the channels 46 which
are in alternation with the dimples 44. As will be appreciated by
those skilled, this arrangement provides enormous surface area for
heat transfer to the reservoir 12.
[0055] In order to further augment the efficiency of the
arrangement, the exchangers 26 provide supports 48 for positioning
the exchangers onto the bottom 50 of the reservoir 26 as shown in
FIG. 6.
[0056] The supports 48 include a vertical component 52 and a
horizontal component 54. The connection of the vertical component
52 is such that the body of the exchanger is angularly disposed
relative to the horizontal. It has been found that this angular
disposition has ramifications in terms of heat transfer to the
fluid in the reservoir. The effective range for the disposition is
from 0.1 degrees to 90 degrees relative to the horizontal. As a
preferred range, the angle may be between 15 degrees and 20
degrees. The vertical component 52 spaces the exchanger from the
bottom 50 (FIG. 6) of the reservoir 12 to facilitate effective heat
transfer. A suitable elevation has been found to be, for example 6
centimeters. This will largely depend on the reservoir volume and
other specific individual requirements. As an option, the elevation
and angle may be changed using suitable linkages and motors (both
not shown) in order to provide the highest de gee of flexibility
for the operator.
[0057] Perhaps one of the most advantageous features of the
arrangement set forth herein relates to the fact that there is no
need for supplementary pumps or other forms of drivers to have
effective heat transfer within the reservoir. This has posed a
problem in the prior art; typically existing systems required
pumping either extraneously or internally of the reservoir to
enable uniform heat distribution. This was necessary to avoid
thermoclines or temperature stratification within the reservoir
which inherently would cause regular cycling of the heating
elements to maintain a uniform temperature. The present invention
has discovered a method to avoid the need for pumps or other
distribution means for the heat.
[0058] It has been found that natural convection can be achieved in
the arrangement by arrangement of the exchangers 26 on the bottom
surface 50 of the reservoir 12. Returning to FIG. 6, the Figure
illustrates D1 D2, D3 and D4 in a counter clockwise array. By
varying the distance in an increasing amount from D1 through with
progressive additions to D4, natural convection has been observed
thus obviating the need for extraneous energy input to induce a
homogeneous temperature. In terms of the useful range between D1
through D4 a ratio 1:1 to 1:7 has been found effective. The result
is very pronounced in light of the previously described heat
exchanger and the secondary heat exchangers. These elements work in
concert to result in an environmentally effective, small footprint
and easily deployable arrangement with the possibility for remote
operation.
[0059] Although four heat exchangers are shown in FIG. 6, it will
be understood that any number of such units may be included in the
reservoir 12. This will, of course, depend on the size of the
reservoir 12 and ambient temperature conditions, etc.
[0060] As illustrated in FIG. 6 by dashed line numeral 52, a cover
layer partially covering the top surface of the reservoir 12 is
depicted. This cover may consist of a suitable buoyant cover that
prevents or significantly reduces evaporation of the fluid from the
reservoir 12, as well as providing an insulating factor to prevent
any temperature drop of the fluid. Suitable materials include, for
example, Styrofoam.RTM., polyethylene, metalized plastic, etc. It
will be readily apparent to those skilled in the art which other
suitable materials may be used.
[0061] In respect of numeral 54, this represents an evaporation
prevention layer which, may comprise, a suitable oil material. An
example of a suitable material would be canola oil as canola oil is
useful for purposes of insulation and preventing evaporation.
Further, the canola oil is useful in that it does not interfere
with the composition of the frac fluid where frac fluid is the
fluid stored in the reservoir 12. Other fluid possibilities have
been mentioned. Provided the liquid cover material does not
interfere with the composition of the frac fluid, any suitable
material achieving the insulation and liquid surface coverage
features could be used and is envisioned for a possibility. Another
example could be a sealed air blanket, suitable foam, etc.
[0062] Turning to FIG. 7, shown is a further possible variation of
the arrangement that could be used in the practicing of the instant
methodology. In this embodiment, numeral 56 shown in dashed line
indicates a further series of heat exchangers 26 which are
vertically elevated from the existing heat exchangers 26 positioned
on the bottom of the reservoir 12 as discussed herein
previously.
[0063] In the arrangement shown, the additional heat exchangers 26
are not only vertically elevated from the existing heat exchangers
26 but also staggered radially therefrom such that a respective
vertically disposed heat exchanger 26 is from a relative distance
point of view adjacent to heat exchangers 26 on the bottom of the
reservoir, in this manner, the entire volume of the reservoir 12
benefits from the heat exchangers in the vertically disposed
position. Simple connectors 56 may be employed to connect the
vertically disposed heat exchangers 26 into the reservoir 12 as
shown by the dotted line represented by numeral 56.
* * * * *